What I'm not sure of is the the resolution. I can resize the project to meet their dimensions and adjust the setting when I render, but how do I adjust the resolution? All I've ever found is basic quality choices such as High, Medium and Low.

I don't think anyone here can give you an answer because they've given you conflicting requirements.IMO, they don't know what they want and just found some stuff online and posted that as their requirements.

In situations like this, I go straight to the source, find the person who is going to post this/upload it(whatever) and ask.

Johnny Cuevas, Editor
Thinkck.com

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.